Method of making containers



METHOD oF MAKING CONTAINERS f Fild June 26, 1940 lNvENToR Clarence WVotg,

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IATToRN Ys l `Patented Dec. 7,

UNITED STATES PATENT OFFICE METHOD oF Mame CONTAINERS Clarence W. Vogt,Norwalk, Conn- Application June 26, 1940, Serial No. 342,478l

t 1s claims.- (ci. isa-5s) l My invention relates to `exible bags and/orliners for cartons and the like, and to novel methods of packagingcommodities in such containers. My invention k,involves the use of thematerial marketed underl the trade name Plioliilm and now in extensiveuse, and to similar materials having the following characteristic propyerty. Pliolm, which is a composition with a rubber base and is in theform of a thin, flexible,

at temperatures nearing or below the freezing point. Thesame materialused in a modified form as plasticizers, as for example, the grade knownas P-4A, has been found to be approximately thirty times stronger afterthe heating, stretching and cooling treatment as compared to the samematerial prior to such treatment.

The term tensilize is herein used to designate the stretching orexpanding operation above pointed out. By the expression tensilized asapplied to a material or bag, is meant a material or bag which has beenheated, softened, stretched or expanded to greatly increase itssupercial area, cooled while in said expanded condition, and whichthereafter retains to a large degree its expanded conditionindependently of extraneous tensile forces.

Advantage has been taken of thel above noted property of Pliolm in itsuse as a covering'material or container fjor various commodities.However, when the Pliofllm has been tensilized, that is. heated,stretched and cooled in the manner above indicated, and it is thereafterreheated to or near the temperature at which the stretching took place,and then cooled, it has a strong tendency to shrink to o r below itsoriginal vsupericialv the tensilizedmaterial impracticablel andespecially so for making the cross-,seams which are of bags.

desirable in the economical manufacture sacks or liners for bags orcartons. An object of the presentinventicn is diiiiculty. To this end Ihave provided novel methods and apparatus for heating and-stretching abag or liner of Pliotilm or like stretchable v to'provide.

a method and means for overcoming the above `area. This fact makes heat'sealing or welding of bag shown in Fig. 1.

or container of -thermoplastic stretchable material to permanentlyincrease its capacity while; supported within an outer container orcarton., and for filling and sealing the container.

A further object of the invention is to provide a novel method andapparatus by which a bag or liner contained within an outer casing orcarton of much greater capacity than the bag may be permanentlystretched and expanded to a capacity commensurate with that of thecontainer,

and thereafter filled with' a commodity and sealed.

A further object of theA invention is to provide a nove1 method and.means for heating and expanding a bag or container of thermoplasticiiexible material, and confining the heating and stretching operationsto predetermined portionsv of the container exclusiveof the mouth andbottom cross seal, and permitting heat sealing of the container at saidmouth.

Other objects of the. invention will appear hereinafter.

Referring to the accompanying drawing:

Fig. 1 is a perspective view oi a collapsed carton with la comparativelysmall bag positioned therein.

Fig. 2 is a longitudinal section of the carton and Fig. 3 is aperspective view showing the carton squared up or open, with'the bagstill collapsed and resting against or'attached'to one panel of thecarton. y

Fig. 4 is a longitudinal section through the open carton and showingmeans for heating, inating and stretching the bag.

Fig. 5 is a sectional elevation of a modification in which the bag isbeing expanded and simul-v taneously lled with a hot liquid.

Fig. 6 is a cross-section at the line 6 6 on Fig. 4. f

Fig. 7 is a similar view of a modification.

Referring particularly to Figs, 1 to 4`and 6; I

have illustrated a method and apparatus by which a bag II! of Pliofilmor like stretchable thermoplastic materiall may be heated and expandedwithin la carton II of much greater 'Y capacity than that of the bagbefore the latter is the material to shrink or shrivel when cooled.

heated and expanded. The bag when expanded f provides a liner for thekcarton and may be iilled with anydesired commodity and sealed. thecarton-naps being thereafter folded and sealed in a conventional mannerto complete the package.

The carton, which may be of conventional form and construction,comprises vertical sides or panels I2 iiexibly connected along theirlongitudinal edges I3. Eachy end -ofthe carton comprises foldable endiiaps I4 onv opposite panels and comparatively narrow end flaps I5on'the intermediate panels. The flexible bag or liner A further Object0f my invention is to provide' co I0 may be made in accordance withconventional a novel method and apparatus ior'stretching a bag methodsby cutting a suitable length from a tube of the material. Such tube mayalso be formed conventionally by progressively folding a web of thematerial to tubular form with the longitudinal edges overlapped orjuxtaposed and heat sealing to form a longitudinal seam. The bag asshown is much shorter than the carton. The lower end of the collapsedbag is closed by a transverse seal along the sealing area I6 (Fig. 1).If desired a band I1, made of paper or other flexible material, may beattached to the upper margin of the bag for reinforcing the bag and, ifdesired, may be provided with printed matter or other markings ordecorations; The bag as shown'is attached to one of the end flaps Il bygluing or adhering theband I1 to the carton flap but, if preferred, mayremain detached from the carton or be attached at a single spot orrelatively small area.

When it is desired to use the carton for packaging a commodity, whichmay be either a liquid, a granulated or comminuted material, or anarticle or material in some other form, the collapsed carton (Fig. 1)with a bag therein, is first squared up as shown in Fig. 3. The mouth ofthe bag I is then opened, a nozzle I8 inserted, and the open mouth ofthe bag clamped to the nozzle by clamps I9. One ofthe clamps extendsinside the carton flap I4 between the ilap and the juxtaposed bag. Theother clamp is positioned outside of the adjoining carton flap so thatthe bag may remain attached to the flap.

A pair of electrical heating elements 2I is positioned within the cartonon opposite sides of the bag Il). Each heating element includes re-vsistance coils 22, the temperature of which is thermostaticallycontrolled in a conventional manner. The heating elements may beintroduced into the carton through the lower end thereof, each saidelement having attached thereto a rod 23 or means for manipulating themand holding them in position. A gripping device 25 is adapted to gripthe lower end of the bag and is used for stretching the bag downwardduring the expanding operation. The gripping device comprises a pair ofjaws pivoted at 26 and connected to the upper end of a rod 21. A wedge28 on the upper end of a tubular rod29, surrounds the rod 21 and ismovable up and down on the rod 21 for actuating the gripping jaws.

By reference to Fig. 6 it will be seen that the jaws 25 are extendedlaterally to about the full width of the bag I0 so as to gripsubstantially the full length of the sealed end I6. It will also benoted that the inner walls of the heating elements comprise off-setportions 30 to provide clearance for the gripping jaws, permittingtheheating elements to be drawn downward past the jaws. The gripping jawsare made to engage substantially the full width of the bag tn facilitatean even and symmetrical expansion of v the bag.

With the parts in the Aposition shown in Fig. 4, heated air undermoderate pressure is supplied through the nozzle I8, thereby partiallyinflating the bag and causing the side walls thereof to Acontact withthe walls of the heating elements so that the portion of the bag incontact with the heatingelements is quickly heated to a temperature atwhich it is softened, so as to permit the walls of the bag to bestretched. The air t almost instantaneously. the heating elements are F.and under withdrawn downward out of the carton;v The gripping device 25is thendrawn downwardly, stretching the bag lengthwise while at the sametime the heated air under pressure entering the bag through the nozzleI8, stretches and expands the bag laterally. The `bag is tfuspinfiated,stretched and enlarged to substantially the full capacity of the carton,with the walls of the bag conforming to and lining the inner wallsurfaces of the carton. When the bag cools it retains most of itsexpansion. It may then or later be lled with the desired contents. Afterexpansion and/or filling of the bag, the bottom aps of the carton areclosed and` sealed.

If it is desired that the bag should serve as a permanent liner for thecarton,` this can be accomplished by applying adhesive material in'stripsspots or over the entire interior surface -of the carton so thatwhen the bag expands and contacts with the carton walls, it will adherethereto and thereafter remain fixed to the carton walls. After thetensilized bag has been lled with a desired commodity, the mouth of thebag is closed and may be heat sealed in a conventional manner by theapplication of heat and pressure which softens the material and weldsthe sides of the bag together along the mouth thereof. As this portionof the bag has not been previously heated and stretched or expanded, noundue contraction or shriveling occurs in connection with the heatsealing. After the bag has been sealed, the carton flaps are folded downand sealed in the usual way to complete the package. Other means thanheat sealing may be employed for closing the mouth of the filled bag as,for example, by gluing or cementing the edges together, or attaching ametal clip or other clamping means.

The extent to which the bag may be stretched depends largely upon thetemperature employed. Comparatively high temperatures, which render thematerial quite soft, permit the stretching or expansion to be carriedfarther than with lower temperatures. If desired, the bags may bestretched to ve or six times their original superficial area. I havefound that it is desirable to expand the bags to a somewhat greaterVolume thanthat which is desired they should retain when cooled. Thereason for this is that the Pliolm tends to contract during and/orshortly after cooling. For example, I find that Plioiilm of .0025 inchthickness when stretched to approximately one-third of its thickness,takes a set of approximately 15% so that if a nal expansion of 300% isdesired, the material should be stretched to about 350% of its originalsuperficial area. This percentage varies with the stretchingtemperatures. Below F. it is necessary to stretch the material tofaboutfive times` its original area to obtain a resultant stretch of 300%.When higher temperatures are employed, the contraction upon cooling isless. This partial contraction, after heating and stretching. providesan elasticity which is particularly advantageous in preventingsubsequent ruptures from rough usage to which the lled container may besubjected during shipment and in handling.

Fig. 5 illustrates a modified method which is particularly adapted foi`use in filling a bag or package with oil or other liquid. In accordancewith this method the electrical heating elements are dispensed with. Theliquid at a temperature of approximately 200" F. is introduced into thebag through the nozzle I8 under a pressure of approximately 1lb. persquare inch. The hot liquid immediately heats the-walls of thebag,permitting it to expand. At the same time the gripping jaws 25 aredrawn downwardly with a, pull of approximately 1 lb. per linear inch ofthe periphery of the bag. This downward pull on the bag combined withthe expansive force of the entering liquid causes the bag to stretch.

or expand both downwardly and laterally, thereby substantiallycompletely filling the carton.

- tainer, and gripping the ends of the container 'o After the liquid hasthus filled and expandedv the bag, and thereby filled the carton, thefilling nozzle and the clamp are withdrawn and the mouth of the bag isclosed and heat sealed. During the lling operation the lower sealed endof the bag is protected from the heat by the jaws 25v and the upper end0f the bag is also pro-f tected from the heat bythe nozzle and clampingmembers I9so that there is no expanding of this portion of the bagduring the filling operation. Accordingly, no undue contraction orshriveling .is induced by the heat sealing operation. .l lAfter the bagis sealed, the carton flaps are folded down and sealed or otherwisefastened to complete the package.

Fig. 7 illustrates a modified construction in which the heat sealingelements on opposite sides of the bag are united in a single structure2|a surrounding the bag and serving to contact the entire periphery ofthe bag. As here shown, the

bag is formed with a longitudinal seam il!8L which extends along onefold of the bag. Modifications may be resorted to within the spirit andscope of'my invention.

I claim:

ing the wall portions of the'containerwhich are -to'be expanded andthereby softening said walls,

applying uid pressure to the interiorl of the container .through an openend thereof and thereby causing lateral expansion of the conand drawingit to a predetermined length by a stretching force applied exteriorly ofthe container to said ends during said lateral expansion.

4. The method of increasing the capacity of a container consisting of aflexible, thermoplasticl sheet material which, when heated and renderedplastic, maybe stretched and expanded to greatly increase itssuperficial area andv which when again cooled will to a large degreeretain its expanded condition, which method comprises applyinglocalized-heat to the.- exterior surfaces of the wall portions of thecontainer which are to 1. The method of increasingthe capacity' of acontainer consisting of.a flexible, thermoplastic sheet material which,when heated and .rendered plastic,'.may be stretched lengthwise ofthecontainer and expanded circumferentially to greatly increase itssuperficial area and which when again cooled will to a large degreeretain its expanded condition, .which method comprises applyingvlocalized heat to the -exterior surfaces of the wall portions of thecontainer which are to be expanded and thereby softening saidwalls.applying fluid pressure within the container and applying a forcelengthwise of` said Walls to thereby expand and lengthen said walls andgreatly increasing their superficial area, and cooling the containerwhile in said expanded condition.

e 2,. The method of increasing the capacity of a be expanded and therebysoftening said walls,V

stretching the container lengthwise and apply-..

ing fluid pressure within thel container to thereby greatly increasetheir supercial area, cooling the container While in said expandedcondition, land controlling the lateral expansion of the container anddetermining its vexpanded size and shape byvconflning walls in the pathof the expanding walls of the container.

"5. The method of enlarging a bag consisting -of a thermoplastic sheetmaterial having the lthe bag andl stretching it lengthwise to a 'prede.

termined length during said lateral expansion.

container consisting of a flexible, thermoplastic sheet material which,Vwhen heated and rendered plastic, may be stretched and expanded togreatly increase its superficial area 'and which when 6. The method ofenlarging-a bag consisting of a thermoplastic sheet-material having thecharacteristic property of being extensible to increase its surface areato a large degree when heated, softened and subjected to 'a stretching force and which will retain ,to a large degree its extended conditionwhen again cooled, which method comprises heating the side walls of thebag to render them plastic, introducing a heated fluid through an openend of the bag, causing the bag tobe expanded laterally by the pressure"of said fluid, gripping the ends of the-bag and drawing it to apredetermined length by a 1ongitudinal stretching force appliedvconcomitantly with said lateral expansion, surrounding the bag againcooled will to a large degree retain its expanded condition, whichmethod comprises heating the wall portions o'f the container which areto be expanded and thereby softening said walls, applying fluidpressure' to the interior of the container and gripping and applyinga'stretching force to the 4container at a point exterior theretoconcomitantly with `said applicationv of fiuid.

pressure and thereby expanding the plasticl walls of the container, andcooling said walls while they areretained in their expanded condition.

3. The method of increasing the capacity v-of a container consisting` ofa flexible, thermoplastic sheetmaterial which, when heated and rendered'plastic, may be stretched and expanded to .greatly increase itssuperficial area. and which when again cooled will to a large degreeretain its expanded condition, which method comprises heatby wallspositioned to arrest thelateral expansion and determine and control thesize and shape of the expanded bag, and cooling the bag after saidexpansion and causing it to retain its expanded condition independent ofextraneous means.

7. The method of enlarging a bag consisting of a thermoplastic sheetmaterial having the characteristic property of being extensible toincrease its surface area to a large degree I'when heated, softened andksubjected to a stret/ching force and whichwill retain to. a largedegree its extended condition when again cooled, which method comprisesapplying. localized heat to the exterior wall surfaces of the bag andthereby heating the body portion of the bagto render it soft and plasticwhile retaining anA open'end portion of the bag `at a comparatively lowtemperature. expanding the body portion of the bag by stretching forceapplied thereto and thereby greatly extending the area of said walls andcorrespondingly increasing -the capacity of the bag, and then coolingthe bag while retaining to a large extent its expanded condition,thereby greatly increasing the capacity of the bag and alsomaterially-increasing its tensile strength.

8. 'Ihe method of forming a package which comprises positioning withina' carton a bag of thermoplastic stretchable material, said bag being ofmuch smaller capacity than the carton, introducing a heated'liquid underpressure into the bag through an open end thereof, thereby heating andstretching the walls of the bag laterally, and applying a stretchingforce exteriorly of the bag to the opposite ends thereof during theiilling of the -bag and thereby causing it to be stretched and expandedlengthwise of the carton.

9. The method which comprises positioning a collapsed bag ofthermoplastic material within an empty carton, said bag being open atone end thereof, positioning heating elements adjacent the walls of saidbag, introducing a uid under pressure into said bag through the open endthereof and thereby expanding the walls of the bag into contact withtheheating elements, and causing said walls to be heated and renderedplastic, thereafter removing said heating elements while continuing theapplication of fluid pressure within the bag, and thereby causing thelatter to expand and stretch in a manner to greatly increase itscapacity and cause it to line the walls of the surrounding carton.

10. The method which comprises positioning a collapsed bag ofthermoplastic material within an empty carton, said bag being open atone end thereof, positioning heating elements adjacent the walls of saidbag, introducing a fluid under pressure into said bag through the. openend thereof and thereby expanding the walls of the bag into contact withthe heating velements and causing said walls to be heated and renderedplastic, thereafter. removing said heating elements while continuing theapplication of fluid pressure within the bag, thereby causing the latterto expand and stretch in a' manner to greatly increase its capacity andcause it to line the walls of the surrounding carton, and applying tothe bag at the end opposite saidopening and during the expansion of thebag a stretching force lengthwise of the bag whereby the bag iselongated as 'it' is expanded laterally by said iiuid pressure'.

11. The method which comprises gripping the opposite ends of a collapsedbag having an opening at one end thereof, said bag consisting ofmaterial expansible under av stretching force, pulling the gripped endsof the bag and thereby stretching the bag lengthwise `and greatlyincreasing itslength, and simultaneously applying iiuid pressure throughsaid opening yand thereby causing thebag4 to expand laterallyAwhile'being extended lengthwise.

12. The method of inila'tingL a collapsedbag having an opening at one'end thereof and consisting of flexible thermoplastic sheet materialAwhich, when' heated and rendered plastic. may be stretched and expandedto greatly increaseits superficial rarea-and` which, when again cooled,will to a large degree retain its expanded con assume and therebygreatly increasing the length of the rb'ag, and simultaneously expandingthe bag laterally by. gaseous pressure introduced through said openingwhile the bag is being extended lengthwise.

13,'The method of infiating a collapsed bag having an opening at one'end thereof and consisting of fiexible thermoplastic sheet materialwhich, when heated and rendered plastic, may be stretched and expandedto greatly increase its superficial area and which, when again cooled,will to a large degree retain its expanded condition, which methodcomprises gripping the ends of the collapsed bag and stretching itlengthwise by pulling on said gripped ends and thereby greatlyincreasing the length of the bag, simultaneously expanding the baglaterally by gaseous pressure introduced through said opening while thebag is being extended lengthwise, and conl trolling the lateralexpansion of the bag and determining its cross-sectional area and shapeby confining walls in the path of the expanding walls of the bag.

14. The method of expanding within a carton, a bag consisting ofthermoplastic sheet material having the property of vbeing extensible toincrease its surface areato a large degree when heated, softened andsubjected to a stretching force, which method comprises, positioning thecollapsed bag within the carton, anchoring one end of the collapsed bagto a,wall of the carton, heating the side walls of the collapsed bag torender them plastic, introducing a fluid into the bag at said anchoredend thereof, causing the bag to be expanded laterally by the pressure ofthe iiuid therein, gripping the opposite end-of the bag, and stretchingthe bag lengthwise within the carton by a stretching force exterior tothe bag and applied simultaneously with the application of said iiuidpressure and thereby causing the bag to be elongated as it expandslaterally.

' 15. The method of packaging a commodity which comprises introducinginto a carton a bag of thermoplastic sheet material which is extensibleto increase its surface area to a large degree when heated, said bagbeing much shorter than y the carton anchoring one end of the bagto adition, andat the same time will have increased tensile strength whichmethod comprises gripping the .ends of the collapsed bag and stretchingit lengthwise by pulling on said gripped ends wall of the cartonadjacent one end thereof, in troducing said commodity into the bagthrough an opening at said end of the bag, said commodity being at atemperature to soften the bag, and gripping the opposite end of the bagand stretching it lengthwise within the carton to sub- .s 'stantiallythe full length of the carton while said commodityis being introduced,whereby the bag is caused to expand and substantially ll the carton.

16.` The method of increasing the capacity and tensile strength of acontainer consisting of a ilexible thermoplastic sheet material which,when heatedand rendered plastic, may be 'stretched and expanded togreatly increase its surface area, yand which, when restored to coolcondition, will to alarge degree retain its expanded condition and atthe same time will have increased tensile strength, whichmethodcomprisesv heating the walls of said container to soften them,applying mechanical force to stretchand fluid pressure to expand thewalls of said container while they are soft to increase their surfacearea and cooling the container walls in said expanded condition. Y v

cLAanNcEw. voor. y

